I'm on a Mac (10.8 Yosemite) and have installed Inkscape 0.91. The fonts listed in Inkscape under the Text tool are numerous but few are actually available.
How can I install additional fonts that will be usable in Inkscape? I understand that bitmap fonts will not be usable in Inkscape so what does this restriction signify?
Can the list currently shown in Inkscape be paired sown to just available/useable fonts?

Well, I'm not a Mac user, which is why I haven't tried to answer this question. What I know for sure, is that Inkscape can only use fonts that are installed on the system, no matter what kind of system.

If I recall, from messages in the past, Macs handle fonts differently from Windows. In Windows, there is only 1 font folder, and if the fonts aren't installed there, Inkscape can't use them. But I seem to recall that Macs are different, and can used fonts from different folders.

Oh wait! There some info in the User FAQ on the website, about fonts. It's more about missing fonts, but here's a link. Maybe it contains enough info to help you? There's some other info on Macs on this page too.

FAQ #C.17.c. https://inkscape.org/en/learn/faq/#Inks ... ts_(on_Mac)

I'm sorry I can't answer your specific questions